1. Field of the Invention
The present invention relates to a display device which performs a display control of pixels using thin film transistors (TFT), and a manufacturing method of the display device.
2. Description of the Related Art
In a display device such as a liquid crystal display device, there has been known an active-matrix-type display device which performs a display control of pixels using low-temperature poly-silicon thin film transistors (LTPS-TFT). A semiconductor film used in the thin film transistor is made of polycrystalline silicon (poly-Si) which is formed due to crystallization by annealing amorphous silicon (a-Si) using laser beams or the like, for example. The semiconductor film used in such display devices is, in general, configured such that the semiconductor film includes a channel layer in which a channel is formed in response to a voltage of a gate electrode and source/drain regions (N+ regions) which are doped with impurities and are connected with source/drain electrodes, and the LDD (Light Doped Drain) structure is formed between the channel layer and the source/drain regions. The LDD structure forms a region which is doped with impurities such that the region exhibits lower concentration than the source/drain regions. The LDD structure is provided for preventing deterioration of hot carriers of the thin film transistor and for lowering an OFF current by alleviating the concentration of an electric field in the source/drain regions.